Allah says in The Noble Qur'an: "The Believers are but a single Brotherhood." [Al-Hujurat 49:10]
The Messenger of Allah (SWT) said, "When Muslims are angry with each other for three days. If they do not compromise then they go away from the limits of Islam and the one who compromise first will enter Jannah (Paradise) earlier."
The Messenger of Allah (SWT) said, "The Muslims are like a body, if one part of the body hurts, rest of the body will also suffer."
The Messenger of Allah (SWT) said, "Believers are brethren, their lives are equal to each other and they are as one hand against their enemy."
The Messenger of Allah (SWT) said, "It is not permissible for two Muslims to be annoyed and angry for more that three days."